In a court hearing, Adams admitted to shooting and killing Trapuzzano on West 16th Street in the early morning hours of April 1, 2014. Prosecutors believed Adams tried to rob Trapuzzano while he was on his daily morning walk.

According to the terms of the plea, Adams is expected to be sentenced to serve 55 years executed in the Indiana Department of Correction. Since the murder occurred before a change to the law, he could get out in half that time with good behavior.

She said her family agreed to the plea deal because it was the best option available, but that they believed Adams should have qualified for life in prison.

"It’s just really hard for me to fathom that any amount of time punishes someone for taking the life of another person," Trapuzzano said.

Curry told CBS4 that because Adams was 16 at the time of the murder, it would've been nearly impossible to get a life in prison sentence. He would have faced 45 to 65 years, had a jury convicted him.

Jennifer Trapuzzano, Nathan's widow, gave birth to the couple's daughter Cecilia three weeks after he died. At a walk in his honor last month, she said the support from family and complete strangers was a blessing.

"It’s fun to see everyone here and show how great Nate was by giving back to others who need help," Trapazzano said.

Proceeds from that walk went to benefit the Nathan Foundation, set up in Trapuzzano's name to raise money for children who have lost a parent.

Shayne Trapuzzano said that she had already been involved in talks about the law and could see herself taking opportunities in the future to advocate for other families. Her family was also upset that Adams was on the streets at all the day he killed her brother, since he was on probation and house arrest at the time.

"The justice system didn’t work. (It) didn’t protect Nate and it’s not protecting other people when it works this way," Shayne Trapuzzano said.

Still, she said the focus now is on remembering her brother and the life he could have led.

"Remember Nate, don't remember this case," she said.

A sentencing hearing is scheduled for July 24 at 1:30 p.m.

Prosecutor Curry released this statement:

“The conviction of Simeon Adams for this tragic and senseless crime was important for the entire community, as so many have grieved with the Trapuzzano family over the loss of Nathan. I commend IMPD’s officers and detectives for their investigation and identification of Adams just days after the incident.”